河道變遷에 의해 形成된 河岸堆積地에 關한 硏究 - 榮山江中流를 對象으로-

Abstract

1. This thesis tries to investigate the forms and sedimentary facies of point bar formed in the changing process of the straight channel which has appeared recently at Mid Youngsan River (Damyang-Youngsanpo), and furthermore to compare them with the sedimentary facies of the point-bar in the bends of a free meander.

2. In this study, the author analyzes the longitudinal profile of the straight channel (water level and bed relief) to explain the relationship between the river meander and the energy equilibrium. Also, he examines in detail the plans of the straight channel change aiming to elucidate the formation of

the bar and the processes of the river channel change. Finally, his concern is devoted to the distribution of the grain size on the surface of the point-bar in D-chute and the succession of the sedimentary facies for the clarification of the formation processes of the Point-bar.

3. The characteristics of the river channel changes and the sedimentary facies of this point-bar are as follows; (1) The straight channel begins to meander in the processes of redressing the disequilibrium of energy consumption which results from the increase of slope due to the formation of the straight channel and the difference in the slope of water level at pool and riffle.

(2) Although the sedimentary facies of this point-bar are similar to that of a free meander, the upward-fining sequences are disrupetd by the gravels which intercalated the bedding-plane.

(3) The point-bars of this river, characterized by low sinuosity and flash flow, are formed by the vertical accretion from the movement of gravels at peak flood and the lateral accretion from the movement of dunes and ripples after peak flood.